Overview
A bounce is the number one enemy of email deliverability. A bounce rate that’s too high can damage your domain reputation, and if it persists over time, it can cause your emails to land straight in spam. Understanding what a bounce is and how to prevent it is essential for any effective outbound email strategy.
Key benefits
Protect your domain reputation in the long run
Improve deliverability and open rates
Avoid spam filters and provider blocks
Secure your outbound campaigns, even at scale
What is a “bounce”?
An email bounces when the recipient’s mail server rejects the message and sends it back to the original sender.
There are two types of bounces: soft bounces and hard bounces.
Types of bounces
Soft bounce
The email address exists, but the message couldn’t be delivered for temporary reasons, such as:
Inbox is full
Mail server is temporarily down
Message or attachment is too large
Email blocked due to its content
DMARC not configured
Message delayed and eventually dropped
Tip: many soft bounces are related to poor domain configuration. Make sure your email certificates are properly set up.
Hard bounce
The email address is invalid or does not exist.
👉 This is the worst-case scenario.
Hard bounces send a very strong negative signal to email providers.
What are the risks of a high bounce rate?
Bounces often occur when using aggressive mass outbound strategies, for example:
Buying email lists
Sending emails to unverified contacts
Using unreliable email sources
A high bounce rate tells email providers and receiving servers that your domain cannot be trusted.
Important:
A consistently high bounce rate can:
Damage your domain reputation
Severely reduce deliverability
Eventually push your emails into spam
That’s why bounces are the enemy.
How can I avoid bounces?
Check your domain’s technical configuration
First, review the technical fundamentals:
These elements are mandatory to prove your identity to email servers.
Check your email source
Where your emails come from matters a lot.
Emails enriched with La Growth Machine
If you use La Growth Machine to enrich emails:
LGM only provides verified emails, as long as risky emails are not enabled.
This is the safest approach, although it can result in lower enrichment rates.
Note: check our guide on risky emails to understand when and why you might enable them.
Emails from external sources
If you import emails from external tools or databases:
La Growth Machine does not verify their validity.
You must validate them yourself using email verification services such as Zerobounce.
Pro tip: always validate external email lists before launching a campaign.
FAQs
What’s the difference between a soft bounce and a hard bounce?
What’s the difference between a soft bounce and a hard bounce?
A soft bounce is temporary (full inbox, server issue), while a hard bounce means the email address does not exist.
What bounce rate is acceptable?
What bounce rate is acceptable?
Ideally below 2%. Above that, your deliverability starts to be at risk.
Are hard bounces worse than soft bounces?
Are hard bounces worse than soft bounces?
Yes. Hard bounces are a strong indicator of poor list quality.
Do risky emails increase bounce rates?
Do risky emails increase bounce rates?
They can increase risk. Use them carefully and only if you understand the impact.